404 ute radio reception
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Thread: 404 ute radio reception

  1. #1
    Fellow Frogger!
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    Default 404 ute radio reception

    Hello there,

    Basically AM radio reception has crackily interference when running. FM perfect. Everything perfect when engine stopped.

    So what has been done. The first radio in the ute was an early digital radio with an aerial on the back of the cab. A new radio was fitted with a CD player and USB port.....no change.
    A different aerial in a different position was fitted....no change.
    Alternator has been upgraded to an 80 amp unit....no change.
    Alternator belt removed and car run.....no change.
    SR 505 electronic ignition fitted....no change.
    New plugs, SR plug extenders instead of original springs....no change.
    Different new leads fitted....no change.
    The only things to have survived is the distributor cap and rotor button.

    Obviously I have electrical interference.....but from where. I am stumped.
    Regards Bob

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    pur-john, not pew-john! peujohn's Avatar
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    Are you parked under a power line as you work or is that too silly?
    John W

    1979 Peugeot 504 GTI 2.2 litre 5 speed - 72 kW at the wheels

    1974 Peugeot 504 TI
    - now on the road

    2009 Peugeot 407 HDI wagon - family car

    Previous: 2005 407 HDI manual sedan, 1980 504 GL, 1990 405 Mi16, 1977 504 GL Special, 1984 505 SRD Turbo



  3. #3
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Bob D View Post
    Hello there,

    Basically AM radio reception has crackily interference when running. FM perfect. Everything perfect when engine stopped.

    So what has been done. The first radio in the ute was an early digital radio with an aerial on the back of the cab. A new radio was fitted with a CD player and USB port.....no change.
    A different aerial in a different position was fitted....no change.
    Alternator has been upgraded to an 80 amp unit....no change.
    Alternator belt removed and car run.....no change.
    SR 505 electronic ignition fitted....no change.
    New plugs, SR plug extenders instead of original springs....no change.
    Different new leads fitted....no change.
    The only things to have survived is the distributor cap and rotor button.

    Obviously I have electrical interference.....but from where. I am stumped.
    Regards Bob
    Is the interference affected by engine revs, ie the noise changes with the engine revs ?

    Does the noise stop/ reduce when aerial is unplugged from the radio?

    Is the noise crackles, hash or whine?

    Is the radio case separately earthed to really good ground point ie the firewall ?

    Is the area where the aerial grounds clean and shiny, if it's on guard a separate earth (to the firewall) is a good idea.

    Earth leads should be at least 15 amp cables, short as practical, terminated in soldered or crimped lugs. The connection points should cleaned to shiny bare metal. An earth from the battery negative to the front sub frame is a good idea too. I believe the main battery earth in the 404 goes to the engine. Check that is sound and clean.

    First step is to find where the noise is being injected, ie dc power lead or antenna (or rarely speaker cables)

    I may have a few more suggestions based on your answers to the questions.
    Last edited by robmac; 6th November 2015 at 09:31 PM.
    The less one interacts with rude, ignorant, critical and argumentative members. The more peaceful life becomes.

  4. #4
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    Well here goes.....
    Alternator is not connected at moment. Just freewheeling.
    It cackles rather than a whine. Interference increases with revs.
    Speakers are in the door and have not changed from original radio.
    Have not unplugged radio and checked interference.
    John, car is nowhere near interference and is not registered yet so only wanders around paddock on test drives.

    Will unplug aerial tomorrow and try radio.
    Earth....I used the original earth wire and will check grounding tomorrow.
    A good start....thankyou gentlemen.

  5. #5
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    Did the old alternator have a noise suppression capacitor fitted [small metal can with wire coming out of it connected between positive terminal and earth ]if so fit it to the new one, pugs

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    1000+ Posts robmac's Avatar
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    Quote Originally Posted by pugwash View Post
    Did the old alternator have a noise suppression capacitor fitted [small metal can with wire coming out of it connected between positive terminal and earth ]if so fit it to the new one, pugs
    The alternator is currently disconnected from the drive belt. So I'd suspect that is not an interference source.
    Impulse noise is normally ignition generated.

    Bob, you could try an earth from the bonnet to the firewall make sure the connections are clean.

    My hunch is the interference is noise from plug leads getting into the aerial.

    You can't have enough earths in "difficult" radio install.
    The less one interacts with rude, ignorant, critical and argumentative members. The more peaceful life becomes.

  7. #7
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    Quote Originally Posted by robmac View Post
    Is the interference affected by engine revs, ie the noise changes with the engine revs ?

    Does the noise stop/ reduce when aerial is unplugged from the radio?

    Is the noise crackles, hash or whine?

    Is the radio case separately earthed to really good ground point ie the firewall ?

    Is the area where the aerial grounds clean and shiny, if it's on guard a separate earth (to the firewall) is a good idea.

    Earth leads should be at least 15 amp cables, short as practical, terminated in soldered or crimped lugs. The connection points should cleaned to shiny bare metal. An earth from the battery negative to the front sub frame is a good idea too. I believe the main battery earth in the 404 goes to the engine. Check that is sound and clean.

    First step is to find where the noise is being injected, ie dc power lead or antenna (or rarely speaker cables)

    I may have a few more suggestions based on your answers to the questions.
    Well, well. I now have this problem too!! I'll be following the thread closely. Nothing changed but alternator!! Noise is ignition when in areas with signal strength down, near high tension power lines, and can just hear the flashing indicator relay giving a click and a hiss when the lights are switched on. I'm smelling earthing myself.

    Thanks again for useful input....
    JohnW

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    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
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    National Co-ordinator, Renault 4CV Register of Australia

  8. #8
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    Hi John,

    Your noises are injected on the power lead I suspect. So an ex dissy condenser to earth on the radio power lead would be worth try as a last ditch attempt.

    Following the earthing advice first which well may eliminate the interference first. Alternator interference usually manifests as a 1-2 khz whine, increasing in frequency with engine revs. Most alternators have a suppressor cap. on the output as harvested/ supplied.
    The less one interacts with rude, ignorant, critical and argumentative members. The more peaceful life becomes.

  9. #9
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    Quote Originally Posted by robmac View Post
    Hi John,

    Your noises are injected on the power lead I suspect. So an ex dissy condenser to earth on the radio power lead would be worth try as a last ditch attempt.

    Following the earthing advice first which well may eliminate the interference first. Alternator interference usually manifests as a 1-2 khz whine, increasing in frequency with engine revs. Most alternators have a suppressor cap. on the output as harvested/ supplied.
    Mine has an old capacitor from positive battery feed (i.e. not D+) to earth on the end of the alternator, so I might replace it with a new one too. There's a capacitor on the regulator from its 12V feed to earth. Since I can just hear the flashing indicators too, that capacitor on the feed to the radio at that end of the car seems a good idea too - thanks.

    This discussion might be helpful on the 404 issue too, so I'm hoping this doesn't act as a complete hijack! I'll get back to the R8 in a few days.

    Cheers
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  10. #10
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    JohnW,
    Feel free to ''hijack'' as you put it. The aim is to help anyone and everyone with a new set of eyes and extended knowledge.
    Go for it is my recommendation.

    The ute....problem solved. When Robmac said to disconnect the aerial and run the motor then we started getting closer as the noise disappeared. What I had forgotten was that the original setup and the new setup both utilised an aerial extension piece as the aerial cables were not long enough. Swapped that over with a spare and problem gone.

    It is great to get a win initiated by the forum. Thankyou.
    Bob
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  11. #11
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by robmac View Post
    Hi John,

    Your noises are injected on the power lead I suspect. So an ex dissy condenser to earth on the radio power lead would be worth try as a last ditch attempt.

    Following the earthing advice first which well may eliminate the interference first. Alternator interference usually manifests as a 1-2 khz whine, increasing in frequency with engine revs. Most alternators have a suppressor cap. on the output as harvested/ supplied.
    I think I've fixed it with a capacitor to earth from the B+ terminal on the regulator. Thanks again.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

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